There is a need for a small, low cost, navigation grade gyroscope for commercial navigation applications. Among the optical gyroscope technologies the resonator fiber optic gyroscope (RFOG) could potentially satisfy those needs by providing better signal to noise sensitivity to rotation rate measurement than the existing interferometric fiber optic gyroscope (IFOG) and the ring laser gyroscope (RLG).
While RFOGs have many advantages over other types of gyroscopes, they still have some issues. One major issue in RFOGs is bias instability, which is a variation in measured rotation rate, or a variation in indicated rotation rate by the gyroscope when the gyroscope is actually not rotating. One source of bias instability is due to light being in the wrong polarization state. Conventional implementations have tried to solve the problem of light being in the wrong polarization state and the temperature dependent errors that occur in PM fibers; however, in trying to solve these problems, conventional implementations have introduced other issues, such as more loss in the resonator (higher gyroscope noise), more assembly cost, larger size, and more imperfections via splices and fiber couplers that introduce performance issues like backscatter and residual polarization errors that limit performance or increase manufacturing tolerance stringency. Moreover, when conventional implementations introduce a large number of splices the ability to use hollow core fiber is diminished, which the use thereof eliminates other error terms. Fusion splices in hollow core fiber are very lossy and mechanical splices are lossy and costly. Each of the above problems in conventional implementations will be discussed in more detail below, along with how the embodiments in the current disclosure solve the above problems.
For the reasons stated above and for the reasons stated below which will become apparent to those skilled in the art upon reading and understanding the specification, there is a need in the art for improved systems and methods for improving the bias instability of RFOGs.